Understanding Knee Osteoarthritis

As the largest joint in the body and the joint that supports most of our weight, the knee joint is subject to a lot of stress.

A new video to our Arthritis-health Video Library explains how knee osteoarthritis progresses and the symptoms it causes.

Learn more: What Is Knee Osteoarthritis?

Watch: Knee Osteoarthritis Video

Knee osteoarthritis is a condition characterized by a breakdown of the cartilage in the knee. This can cause inflammation, pain, and swelling.

The knee joint connects the femur, or thigh bone, to the tibia, or shin bone. The fibula, a smaller bone next to the tibia, is also part of the joint.

The condile, or curved end of the femur, is covered with protective cartilage. Between the femur and tibia is another thick piece of cartilage known as the meniscus. This cartilage acts as a shock absorber for the knee. There is also a layer of cartilage on the underside of the patella, or knee cap.

See Knee Anatomy

Normally, all this cartilage helps the hinge-like movement of the knee occur without any damage to the joint. However, knee osteoarthritis causes the cartilage to start to degenerate because of gradual wear and tear, an injury, or both.

See Knee Osteoarthritis Causes


The first symptoms of knee osteoarthritis are often stiffness or aching pain in the knee. As the condition progresses, the inflamed knee cartilage begins to thin and may even disappear completely.

See Knee Osteoarthritis Symptoms

The disappearance of the cartilage can cause the bones to rub directly against each other. The bone responds to this friction by trying to cushion the joint further with bumpy bone growths called bone spurs or osteophytes. If the osteophytes interfere with the movement of the joint, they can cause further pain.

Watch: Lumbar Osteophytes (Bone Spurs) Video

Another result of the progression of knee osteoarthritis can be the loss of some or all of the range of motion in the knee. It can also weaken the knee, making it unable to bear the weight of the body.

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